1. Field of the Invention
The present invention relates to a system for and a method of sharing photosensitive medium characteristics, which are suitable for use in an image forming apparatus for forming an image by exposing a photosensitive medium and developing the image thereon under image forming conditions depending on the density characteristics of the photosensitive medium, and an image forming apparatus.
2. Description of the Related Art
Photosensitive mediums, e.g., photosensitive thermal-development recording mediums which are exposed to image light to form a latent image thereon and then heated to develop the latent image into a visible image, can be handled with ease as they are processed by a dry development system, rather than a wet development system. However, those photosensitive mediums suffer characteristic variations from production lot to production lot.
In order to form images of good quality on photosensitive thermal-development recording mediums, it is necessary to keep information as to the characteristics of those photosensitive mediums of the respective production lots and expose the photosensitive mediums to image light and develop images thereon under image forming conditions depending on the density characteristics of the photosensitive mediums.
The image forming conditions for photosensitive thermal-development recording mediums include exposure conditions for determining an amount of light to be applied to form a latent image and developing conditions for determining the temperature of a heat source used for thermal development and a period of time in which to develop the latent image.
Photosensitive thermal-development recording mediums are suitable for use as image recording films for medical diagnosis. Therefore, image forming apparatus which employ photosensitive thermal-development recording mediums are typically incorporated in medical facilities.
When such an image forming apparatus is shipped from the factory or installed in a medical facility, image processing conditions depending on the characteristics of photosensitive mediums of a given production lot, i.e., standard image processing conditions, are determined, and the standard image processing conditions are stored in a memory of the image forming apparatus for use in an image forming process.
When all photosensitive mediums included in an image forming apparatus in a medical facility are consumed, new photosensitive mediums are loaded into the image forming apparatus. For the purpose of achieving a desired level of image quality, it is important that the characteristics of the newly loaded photosensitive mediums be the same as the characteristics of the previously loaded photosensitive mediums.
Heretofore, the following process has been carried out to achieve the desired image quality: When new photosensitive mediums, i.e., a package of new photosensitive mediums, are loaded into the image forming apparatus, one of the newly loaded photosensitive mediums is exposed to image light under the standard image forming conditions to form a latent image thereon, the latent image is developed into a visible test pattern image, and the density characteristics of the test pattern image are measured by a densitometer. Then, the characteristics of the newly loaded photosensitive mediums, e.g., corrective conditions for the standard image forming conditions, are determined from the measured density characteristics. See Japanese laid-open patent publication No. 2000-292898 for details.
When a new photosensitive medium is to be exposed to image light to form a latent image thereon and the latent image is to be developed into a visible image, the standard image forming conditions are changed to image forming conditions depending on the determined characteristics of the photosensitive medium, and an image of constant image quality is formed under the changed image forming conditions.
However, since each time new photosensitive mediums are loaded into the image forming apparatus, it is necessary to measure characteristics of the newly loaded photosensitive mediums, the image forming apparatus needs a certain preparatory time before the new photosensitive mediums can be used in the image forming apparatus.
In addition, because the image forming apparatus consumes one of the newly loaded photosensitive mediums to output a test pattern image for measuring their characteristics, an extra cost is spent on the image forming apparatus from the trial print.
A solution to some of the above problems is also disclosed in Japanese laid-open patent publication No. 2000-292898.
The disclosed solution is based on the fact that a plurality of photosensitive mediums are stacked together in a light-shielded state and accommodated in a single package. Specifically, a bar code representing information as to the density characteristics of the packaged photosensitive mediums is applied to the package.
The image forming apparatus has a tray for loading the packaged photosensitive mediums into the image forming apparatus, a mechanism for removing the package from the photosensitive mediums on the tray in the image forming apparatus, and a bar-code reader for reading the bar code on the package.
When the packaged photosensitive mediums are loaded into the image forming apparatus, the bar-code reader reads the bar code on the package, and the characteristics of the newly loaded photosensitive mediums as represented by the bar code are stored in a memory in the image forming apparatus.
Generally, however, a bar code applied to a product records only attribute information such as the production date of the product, the manufacturer of the product, the production lot number, the name of the product, and the code of the product. It is usually difficult for the bar code to record corrective information for image forming conditions as described above, i.e., all the characteristics of photosensitive mediums.
If photosensitive mediums that are handled are photosensitive thermal-development recording mediums, then the corrective information referred above contains a large amount of data. A bar-code system which handles a large amount of data is highly expensive to manufacture.
According to Japanese laid-open patent publication No. 2000-292898, as described above, when a package of new photosensitive mediums is loaded into the tray of the image forming apparatus, one of the loaded photosensitive mediums is exposed to image light to form a latent image thereon, the latent image is thermally developed into a visible test pattern image, the density characteristics of the test pattern image are measured by a densitometer, and the measured density characteristics are stored as the characteristics of the loaded photosensitive mediums. Therefore, each time a package of new photosensitive mediums is loaded into the tray, one of the loaded photosensitive mediums is exposed to image light to form a latent image thereon, the latent image is thermally developed into a visible test pattern image, and the density characteristics of the test pattern image are measured by a densitometer. One of the loaded photosensitive mediums is thus consumed for a trial print, and the image forming apparatus needs a long preparatory time until the characteristics of the loaded photosensitive mediums are obtained. These disadvantages are not resolved in the conventional technique.